Riffing off a POLITICO report on Pelosi's upcoming Napa Valley event for big-dollar donors and other supporters, Beck did a sketch Thursday in which he pretended to be at the event, drinking wine with the speaker.

As a staffer wearing a Pelosi mask lifted a glass to her lips, Beck said:

"I really just really wanted to thank you having me over here to Wine Country, you know. To be invited, I thought I had to be a major Democratic donor, or a long-time friend of yours, which I'm not. By the way, I put poison in your - no. . . . "

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At that point, Beck cut himself off and told the Pelosi doppelganger: "I look forward to all the policy discussions we're supposed to have — you know, on health care, energy reform and the economy. Hey, is that Sean Penn over there? I know it cost me more than $30,000 to get in here, but – Hey! Hey! I think I see Ed Markey, the author of cap and trade, over there."

In a statement, Media Matters President Eric Burns called Beck a "one-man hate machine" and said that "poisoning the House speaker in effigy is just the latest in a long line of actions, statements, and stunts that have no place on a credible news network."

Beck’s comments came amid increasing tension – and reports of shoving and scuffling among attendees – at town-hall meetings held by Democratic lawmakers.

Conservative organizations have encouraged opponents of Democratic health care proposals to go to lawmakers’ public events and express their opposition, but these protests have taken on an increasingly nasty edge in recent days.

Rep. Brad Miller’s (D-N.C.) office reportedly received a death threat against the congressman, and members of an overflow crowd at a Florida town hall banged on the doors and windows of a conference room when they were shut out of the event due to concerns about overcrowding. There were also reports in local newspapers of pushing and shoving at the event, which was held by Rep. Kathy Castor (D-Fla.)

Democrats have vowed to press ahead with their events during the month-long August congressional recess, but senior party officials are privately fearful about the potential for violence at the town halls.

There is definitely a concern about these things turning violent,” said a Democratic strategist, speaking on the condition of anonymity.

This source said party officials are telling their members to take security precautions, especially if a large crowd is expected to attend a public appearance.

Earlier this week, Pelosi dismissed the town hall disturbances as “Astroturfed” – and not the product of genuine grassroots anger over the Democrats’ health care proposals.